import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';

import 'package:household_keeper/core/database/database.dart';
import 'package:household_keeper/core/providers/database_provider.dart';
import 'package:household_keeper/features/tasks/presentation/task_providers.dart';
import 'package:household_keeper/features/tasks/presentation/task_row.dart';
import 'package:household_keeper/l10n/app_localizations.dart';

/// Screen displaying all tasks within a room, sorted by due date.
///
/// Shows an empty state when no tasks exist, with a button to create one.
/// FAB always visible for quick task creation.
/// AppBar shows room name with edit and delete actions.
class TaskListScreen extends ConsumerWidget {
  const TaskListScreen({super.key, required this.roomId});

  final int roomId;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    final l10n = AppLocalizations.of(context);
    final asyncTasks = ref.watch(tasksInRoomProvider(roomId));

    return Scaffold(
      appBar: AppBar(
        title: _RoomTitle(roomId: roomId),
        actions: [
          IconButton(
            icon: const Icon(Icons.edit),
            onPressed: () => context.go('/rooms/$roomId/edit'),
          ),
          IconButton(
            icon: const Icon(Icons.delete),
            onPressed: () => _showRoomDeleteConfirmation(context, ref, l10n),
          ),
        ],
      ),
      body: asyncTasks.when(
        data: (tasks) {
          if (tasks.isEmpty) {
            return _EmptyState(l10n: l10n, roomId: roomId);
          }
          return _TaskListView(
            tasks: tasks,
            l10n: l10n,
          );
        },
        loading: () => const Center(child: CircularProgressIndicator()),
        error: (error, stack) => Center(
          child: Column(
            mainAxisSize: MainAxisSize.min,
            children: [
              Text('Fehler: $error'),
              const SizedBox(height: 16),
              FilledButton.tonal(
                onPressed: () => ref.invalidate(tasksInRoomProvider(roomId)),
                child: const Text('Erneut versuchen'),
              ),
            ],
          ),
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: () => context.go('/rooms/$roomId/tasks/new'),
        child: const Icon(Icons.add),
      ),
    );
  }

  void _showRoomDeleteConfirmation(
    BuildContext context,
    WidgetRef ref,
    AppLocalizations l10n,
  ) {
    showDialog(
      context: context,
      builder: (ctx) => AlertDialog(
        title: Text(l10n.roomDeleteConfirmTitle),
        content: Text(l10n.roomDeleteConfirmMessage),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(ctx),
            child: Text(l10n.cancel),
          ),
          FilledButton(
            onPressed: () {
              Navigator.pop(ctx);
              final db = ref.read(appDatabaseProvider);
              db.roomsDao.deleteRoom(roomId);
              // Navigate back to rooms list
              context.go('/rooms');
            },
            style: FilledButton.styleFrom(
              backgroundColor: Theme.of(context).colorScheme.error,
              foregroundColor: Theme.of(context).colorScheme.onError,
            ),
            child: Text(l10n.roomDeleteConfirmAction),
          ),
        ],
      ),
    );
  }
}

/// Async room name loader for the AppBar title.
class _RoomTitle extends ConsumerWidget {
  const _RoomTitle({required this.roomId});

  final int roomId;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    // Use a FutureBuilder-like approach: read room name from DB
    return FutureBuilder<Room>(
      future: ref.read(appDatabaseProvider).roomsDao.getRoomById(roomId),
      builder: (context, snapshot) {
        if (snapshot.hasData) {
          return Text(snapshot.data!.name);
        }
        return const Text('...');
      },
    );
  }
}

/// Empty state shown when the room has no tasks.
class _EmptyState extends StatelessWidget {
  const _EmptyState({required this.l10n, required this.roomId});

  final AppLocalizations l10n;
  final int roomId;

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);

    return Center(
      child: Padding(
        padding: const EdgeInsets.symmetric(horizontal: 32),
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            Icon(
              Icons.task_alt,
              size: 80,
              color: theme.colorScheme.onSurface.withValues(alpha: 0.4),
            ),
            const SizedBox(height: 24),
            Text(
              l10n.taskEmptyTitle,
              style: theme.textTheme.headlineSmall,
              textAlign: TextAlign.center,
            ),
            const SizedBox(height: 8),
            Text(
              l10n.taskEmptyMessage,
              style: theme.textTheme.bodyLarge?.copyWith(
                color: theme.colorScheme.onSurface.withValues(alpha: 0.6),
              ),
              textAlign: TextAlign.center,
            ),
            const SizedBox(height: 24),
            FilledButton.tonal(
              onPressed: () => context.go('/rooms/$roomId/tasks/new'),
              child: Text(l10n.taskEmptyAction),
            ),
          ],
        ),
      ),
    );
  }
}

/// List view of task rows with long-press delete support.
class _TaskListView extends ConsumerWidget {
  const _TaskListView({required this.tasks, required this.l10n});

  final List<Task> tasks;
  final AppLocalizations l10n;

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    return ListView.builder(
      itemCount: tasks.length,
      itemBuilder: (context, index) {
        final task = tasks[index];
        return TaskRow(
          key: ValueKey(task.id),
          task: task,
          onDelete: () => _showDeleteConfirmation(context, ref, task),
        );
      },
    );
  }

  void _showDeleteConfirmation(
    BuildContext context,
    WidgetRef ref,
    Task task,
  ) {
    showDialog(
      context: context,
      builder: (ctx) => AlertDialog(
        title: Text(l10n.taskDeleteConfirmTitle),
        content: Text(l10n.taskDeleteConfirmMessage),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(ctx),
            child: Text(l10n.cancel),
          ),
          FilledButton(
            onPressed: () {
              Navigator.pop(ctx);
              ref.read(taskActionsProvider.notifier).deleteTask(task.id);
            },
            style: FilledButton.styleFrom(
              backgroundColor: Theme.of(context).colorScheme.error,
              foregroundColor: Theme.of(context).colorScheme.onError,
            ),
            child: Text(l10n.taskDeleteConfirmAction),
          ),
        ],
      ),
    );
  }
}